1. Field of the Invention
The invention relates to a method and a device for shaping workpieces.
2. Background and Related Art
To manufacture components by cold or warm shaping, for example by forging, shaping machines are used in which shaping tools are placed, in particular percussive shaping machines such as hammers, crank presses, and screw presses, and in particular flywheel screw presses. The shaping process is performed on an un-machined workpiece inserted into the tool by pressing or striking the tools together, thereby bringing the workpiece into its desired final shape.
The manufacturing process is automated by the use of handling devices, in particular manipulators and industrial robots, for handling the workpieces. These handling devices take the un-machined workpiece, in a first step usually from a hopper, and position the workpiece between the parts of the tool, usually having a two-piece design, which is placed in the shaping machine. After the handling device is removed from the working region of the shaping machine, the shaping process is carried out by moving the tool halves together. After the tool is opened, the handling device grips the finished workpiece and deposits it in a finished parts hopper.
The process reliability of the shaping process is principally a function of the precision with which the un-machined workpiece to be machined is inserted into the shaping machine, specifically, into the working region, and deposited there. In order to meet these demanding requirements, in the setup of the shaping machine it is necessary to adjust the handling device precisely to the position of the working region of the tool. This is rather laborious and time-consuming, and the setup process is consequently expensive.
After the tool is installed in the shaping machine following a tool replacement, heretofore it has been necessary to orient the handling device to the exact position of the tool. This prolongs the setup time and lowers productivity.
Furthermore, over the course of time the tool may loosen during the shaping process, which is particularly the case for percussive forging die shaping machines. This changes the position and orientation of the tool, making it necessary at certain intervals to realign the handling device relative to the instantaneous position of the tool in order to maintain sufficient process reliability. Heretofore, this adjustment has been performed by checking the points approached by the handling device and making appropriate corrections when deviations are encountered. This also prolongs the setup time and results in corresponding forfeiture of productivity of the unit.
If according to the prior art a periodic checking of the position of the tool and adjustment of the handling device is omitted, it is possible to keep the setup time low and/or achieve high productivity. However, this is achieved at the expense of process reliability or tool wear, since the positioning of the un-machined workpiece by the handling device cannot be ensured with sufficient accuracy. There is the general risk that the un-machined workpiece is inserted too imprecisely into the tool, resulting in the referenced problems.
Another problem which occurs in practice is the so-called “slippage” of the shaping tool, which is understood to mean that after a certain number of lifting operations by the shaping machine, the tool gravures become worn and the tool must be remachined. In this regard, the height of the workpiece is milled down; i.e., a new gravure is thus introduced into the tool. When this tool, the height of which has been changed, is now installed in the shaping machine, a complete realignment or adjustment of the handling device is necessary to avoid the above-referenced problems. This is also at the expense of productivity and/or process reliability of the unit.